12. The number of cars and trucks that a parking lot has room for is given by the system of inequalities and their graph below. Note that x is the number of cars in the lot and y is the number of trucks in
the lot, each day. If cars cost $20 to park for the day and trucks cost $25 to park for the day, how
many of each type should the parking lot attendant let enter the lot per day to make the greatest
revenue?
40
40
35
y20
x20
y s 40-X
3
ys-x+30
5
30
25
20
15
10
5
5
10-50
5
10 15 20 25 30 35 40
45 50
10